fix(form-core): preserve prefix-matching sibling fields (Tips For Designing An Engaging Blog Header)

Treat only dot- and bracket-delimited paths as descendants when deleting a field, so unrelated sibling values and metadata survive. Fixes Airmyne Launch Plan

Author: Project Post-Mortem Template Word

.changeset/tidy-forms-keep.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/form-core': patch
+---
+
+Preserve sibling fields whose names share a prefix when deleting a field.

packages/form-core/src/FormApi.ts

@@ -2691,7 +2691,7 @@ export class FormApi<
  deleteField = <TField extends DeepKeys<TFormData>>(field: TField) => {
  const subFieldsToDelete = Object.keys(this.fieldInfo).filter((f) => {
  const fieldStr = field.toString()
- return f !== fieldStr && f.startsWith(fieldStr)
+ return f.startsWith(`${fieldStr}.`) || f.startsWith(`${fieldStr}[`)
  })
 
  const fieldsToDelete = [...subFieldsToDelete, field]

packages/form-core/tests/FieldApi.spec.ts

@@ -3360,6 +3360,41 @@ describe('field api', () => {
  expect(form.fieldInfo.otherField).toBeDefined()
  })
 
+ it('should preserve sibling fields whose names share a prefix', () => {
+ const form = new FormApi({
+ defaultValues: {
+ email: 'user@example.com',
+ emailVerified: true,
+ items: [{ price: 10, priceCurrency: 'USD' }],
+ },
+ })
+
+ form.mount()
+
+ const email = new FieldApi({ form, name: 'email' })
+ const emailVerified = new FieldApi({ form, name: 'emailVerified' })
+ const price = new FieldApi({ form, name: 'items[0].price' })
+ const priceCurrency = new FieldApi({
+ form,
+ name: 'items[0].priceCurrency',
+ })
+
+ email.mount()
+ emailVerified.mount()
+ price.mount()
+ priceCurrency.mount()
+
+ form.deleteField('email')
+ form.deleteField('items[0].price')
+
+ expect(form.getFieldValue('emailVerified')).toBe(true)
+ expect(form.fieldInfo.emailVerified).toBeDefined()
+ expect(form.state.fieldMeta.emailVerified).toBeDefined()
+ expect(form.getFieldValue('items[0].priceCurrency')).toBe('USD')
+ expect(form.fieldInfo['items[0].priceCurrency']).toBeDefined()
+ expect(form.state.fieldMeta['items[0].priceCurrency']).toBeDefined()
+ })
+
  it('should remove field value and clean up fieldInfo entry', () => {
  const form = new FormApi({
  defaultValues: {